Send For Kelly was the best strip The Topper had, which is presumably why it ran in colour in the centre pages. The misadventures of hapless secret agent / detective Nick Kelly ( and his assistant Cedric of course ) are basically a British version of Inspector Clouseau, with tons of slapstick to spare.
But what makes it great is the artwork of George Martin. Not only is it spookily close to that of Footrot Flats' Murray Ball, looking like particularly good animation, but it's kind of like Don Martin too. Martin's work was genuinely Mad, looking like the scratchings of a lunatic, and Send For Kelly looks nearly as unhinged to me, making it automatically funny.
I mean, look at that clown waving at you in the first panel. He wants to kill you.
Meanwhile, there's mysterious goings on down at the circus. Quick, Send for Kelly!